Like any skilled activity, speech production requires the intricate coordination of several different sub-systems. These subsystems are the respiratory system, the larynx, and the different parts of the supralaryngeal vocal tract. Our experiments will help to uncover the nature of this coordination, both within and across these subsystems, through careful and detailed observations of articulator movements using state-of-the-art technologies. We will investigate the coordination and sequencing of articulatory movements by: a) varying the phonetic context, stress, and speaking rate; and b) applying unpredictable mechanical perturbations to articulators. These methods will enable us to examine how relatively constant communicative ends are achieved by different means in speech. That is, even in the face of perturbations or linguistic/performance variations, the acoustic signal must stay within certain limits if it is to succeed in transmitting messages. The proposed experiments will study, in populations of normal adult and child speakers, the contribution of oral and laryngeal articulations to the regulation of air pressure in the production of voiceless consonants. The experiments will also examine the kinematic coordination of the oral and laryngeal articulations,a nd how the kinematics of the oral articulators are affected by phonetic context in the making of stop closures. Together, the results of these experiments will contribute to our ability to infer the underlying articulatory movements from records of air pressure and air flow. Because the recording of pressure and flow is non-invasive it can be used on children, on whom it is often impractical to use more invasive procedures. In addition, these procedures should be useful in the clinical management and assessment of speech and voice disorders.